From this site [h/t to Jack]:
The camera exposure times were just right to capture the dark-side of its rings, but longer than that required to properly expose the globe of sunlit Saturn. Consequently, the sunlit half of the planet is overexposed. Between the blinding light of day and the dark of night, there is a strip of twilight on the globe where colourful details in the atmosphere can be seen. Bright clouds dot the bluish-grey northern polar region here. In the south, the planet's night side glows golden in reflected light from the rings' sunlit face.
Saturn's shadow stretches completely across the rings in this view, in contrast to what Cassini saw when it arrived in 2004.